Transpeptidation Peptidoglycan (PG) forms the essential structural backbone of bacterial cell walls, providing rigidity and protection against osmotic lysis.Peptidoglycan: Understanding Elongation and Cross Linking ... A critical process in the assembly and maintenance of this protective layer is peptide cross-linking. This process involves the formation of peptide bonds between the peptide side chains of adjacent peptidoglycan monomers, creating a robust, three-dimensional mesh.Reconstitution of Peptidoglycan Cross-Linking Leads to ... This intricate network is fundamental to bacterial survival and is a key target for antimicrobial agents. Understanding the mechanisms and significance of peptide cross-linking in peptidoglycan is crucial for comprehending bacterial cell wall biology and developing new therapeutic strategies.作者：L Alvarez·2024·被引用次数：24—We unveil a novel and widespread control mechanism of lytic transglycosylases (LTs), a type of autolysin responsible for breaking down PG glycan chains.
Peptidoglycan itself is a complex polymer composed of repeating disaccharide units, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), linked together to form long glycan strands. Attached to each NAM residue is a short peptide side chain. The strength and integrity of the peptidoglycan layer come from the covalent bonds formed between these peptide side chains. This cross-linking process is catalyzed by a class of enzymes known as transpeptidases, which are often referred to as penicillin-binding proteins (PBPs) due to their role as targets for penicillin antibiotics.
The process typically involves the cleavage of the terminal D-alanine residue from one peptide chain and the formation of a new peptide bond with an amino acid on an adjacent peptide chain.作者：F Driehuis·1992·被引用次数：17—The glycan chains in peptidoglycan or murein are cross-linkedby transpeptidation of the peptide side chains. This creates a stable, interconnected meshwork that encases the bacterial cell.Control of bacterial cell wall autolysins by peptidoglycan ... The specific amino acid sequence of the peptide side chains and the types of cross-links formed can vary significantly between different bacterial species, including variations seen in peptidoglycan cross linking gram positive and gram-negative bacteria.(a)Peptidoglycan structure with peptide cross-linkingin gram positive and gram negative bacteria. (b) Stereoisomers of diaminopimelic acid (DAP). Source ... These structural differences can influence the overall rigidity and permeability of the cell wall, impacting bacterial physiology and susceptibility to environmental stresses and antibiotics.Identification of the l,d-Transpeptidases for Peptidoglycan ...
The precise construction of the peptidoglycan layer relies on a coordinated effort of various enzymes, with transpeptidases playing a central role in the cross-linking of peptide stems onto the glycan backbone作者：F Driehuis·1992·被引用次数：17—The glycan chains in peptidoglycan or murein are cross-linkedby transpeptidation of the peptide side chains.. These enzymes recognize specific peptide motifs, such as the D-Ala-D-Ala sequence, and facilitate the formation of the peptide bonds that link adjacent peptidoglycan units.
Other enzymes, such as lytic transglycosylases, are also involved in peptidoglycan metabolism, but their primary function is to break down glycan chains, contributing to cell wall remodeling rather than cross-linking. The balance between synthesis, cross-linking, and degradation is tightly regulated to ensure proper cell wall structure and function during bacterial growth and division. Disruptions to this delicate balance can lead to cell lysis or compromised cell wall integrity.
The peptide cross-linking of peptidoglycan is not merely a structural embellishment; it is a fundamental requirement for bacterial viability作者：AJ Apostolos·2022·被引用次数：16—This chapter focuses on the use of solid-phasepeptidesynthesis to build PG analogs that become site-selectively incorporated into the cell wall of live .... The resulting rigid meshwork provides essential mechanical strength, preventing the cell from bursting due to internal osmotic pressure. Without adequate cross-linking, bacteria are highly susceptible to lysis.
Furthermore, the peptidoglycan layer is a critical target for many antibiotics. By inhibiting the transpeptidases responsible for peptide cross-linking, drugs like penicillin effectively halt cell wall synthesis, leading to bacterial death. The high degree of cross-linking observed in certain bacteria, such as *Staphylococcus aureus*, can influence their susceptibility to such antibioticsCross-links consist in a peptide bondbetween the amino group of the amino acid in position 3 of the acceptor peptide stem and the carbonyl group of the amino ....
Research into peptidoglycan structure and the enzymes involved in its synthesis and cross-linking continues to be a vital area of study.作者：DA Dik·2021·被引用次数：9—Thepeptidoglycanis composed of glycan that assembles from the disaccharide pair NAG (shown and labeled in dark green)-NAM (light green). Understanding the intricate details of these processes, including the variations in peptidoglycan structure across different species and the precise mechanisms of transpeptidation, offers pathways for the development of novel antimicrobial strategies to combat the growing threat of antibiotic resistance.Cross-linkage and cross-linking of peptidoglycan in ... The ability to precisely control or disrupt these cross-links is key to unlocking new therapeutic interventionsControl of bacterial cell wall autolysins by peptidoglycan ....
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